1. Field of the Invention
The present invention relates to a fan and a fan wheel thereof, and more particularly, the present invention relates to a fan and a fan wheel thereof capable of reducing the noise while increasing the air flow rate.
2. Descriptions of the Related Art
As a result of the advancement in process technologies, circuit boards of many electronic products are now made to carry electronic components (e.g., central processing units, memories, integrated circuits and the like) at an ever-higher density. Because electronic components generate heat during operation, denser electronic components increases the temperature of the whole electronic product, which may cause abnormal operation of the electronic products or even damage to the electronic components thereof due to intense heat.
In the prior art, a fan is disposed in an electronic product so that air flow produced by the rotating fan can force convection to cool the electronic components thereof.
FIG. 1 illustrates a conventional fan 1 that comprises a fan wheel 11 and a fan cowl 12. The fan wheel 11 comprises a hub 110 and a plurality of blades 111. Each of the blades 111 has a blade width W1 and extends from a side wall of the hub 110.
The conventional fan 1 has a narrower blade width W1, and to maintain certain efficiency in producing the air flow, a large number of blades must be provided. For instance, the conventional fan 1 depicted in FIG. 1 comprises seven blades 111. As a result, the pitch between the blades 111 is inevitably reduced. Moreover, to get a strengthened flow rate and improved heat dissipation efficiency, the rotation speed of the fan wheel 11 must be increased. However, when the fan 1 operates at a high rotation speed, there is too small of a pitch between the blades which will cause disturbance to the air flow fields produced by the blades to each other or even cause annoying noise.
According to the above description, the conventional fan 1 increases the rotational speed of the fan wheel 11 at the cost of exacerbated noise. On the other hand, if the rotational speed of the fan wheel 11 is not increased, the flow rate would be too small, which would be inadequate to deliver the desired heat dissipation efficiency for the dense electronic components.
In view of this, it is highly desirable in the art to provide a fan and a fan wheel thereof capable of reducing the noise while increasing the airflow rate.